Neutron Scattering Evidence for a Periodically-Modulated Superconducting Phase in the Underdoped Cuprate La$_{1.905}$Ba$_{0.095}$CuO$_4$

TL;DR

This study provides neutron scattering evidence that in underdoped La$_{1.905}$Ba$_{0.095}$CuO$_4$, gapless spin fluctuations coexist with superconductivity, with magnetic spectral weight and incommensurability enhanced by superconducting correlations, suggesting intertwined spatial modulations.

Contribution

The paper reveals coexistence of spin fluctuations and superconductivity with enhanced magnetic features, proposing a spatial modulation intertwining of pair wave function and magnetic correlations.

Findings

Gapless spin fluctuations coexist with superconductivity.

Magnetic spectral weight and incommensurability increase with superconductivity.

Evidence supports intertwined spatial modulations of pairing and magnetic order.

Abstract

The role of antiferromagnetic spin correlations in high-temperature superconductors remains a matter of debate. We present inelastic neutron scattering evidence that gapless spin fluctuations coexist with superconductivity in La$_{1.905}$Ba$_{0.095}$CuO$_4$. Furthermore, we observe that both the low-energy magnetic spectral weight and the spin incommensurability are enhanced by the onset of superconducting correlations. We propose that the coexistence occurs through intertwining of spatial modulations of the pair wave function and the antiferromagnetic correlations. This proposal is also directly relevant to sufficiently underdoped La$_{2-x}$Sr$_x$CuO$_4$ and YBa$_2$Cu$_3$O$_{6+x}$.